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Berro Y, Gueddida S, Bouizi Y, Bellouard C, Bendeif EE, Gansmuller A, Celzard A, Fierro V, Ihiawakrim D, Ersen O, Kassir M, El Haj Hassan F, Lebegue S, Badawi M, Canilho N, Pasc A. Imprinting isolated single iron atoms onto mesoporous silica by templating with metallosurfactants. J Colloid Interface Sci 2020; 573:193-203. [PMID: 32278950 DOI: 10.1016/j.jcis.2020.03.095] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 03/12/2020] [Accepted: 03/26/2020] [Indexed: 01/03/2023]
Abstract
HYPOTHESIS One of the main drawbacks of metal-supported materials, traditionally prepared by the impregnation of metal salts onto pre-synthesized porous supports, is the formation of large and unevenly dispersed particles. Generally, the larger are the particles, the lower is the number of catalytic sites. Maximum atom exposure can be reached within single-atom materials, which appear therefore as the next generation of porous catalysts. EXPERIMENTS Herein, we designed single iron atom-supported silica materials through sol-gel hydrothermal treatment using mixtures of a non-ionic surfactant (Pluronic P123) and a metallosurfactant (cetyltrimethylammoniumtrichloromonobromoferrate, CTAF) as porogens. The ratio between the Pluronic P123 and the CTAF enables to control the silica structural and textural properties. More importantly, CTAF acts as an iron source, which amount could be simply tuned by varying the non-ionic/metallo surfactants molar ratio. FINDINGS The fine distribution of iron atoms onto the silica mesopores results from the iron distribution within the mixed micelles, which serve as templates for the polymerization of the silica matrix. Several characterization methods were used to determine the structural and textural properties of the silica material (XRD, N2 sorption isotherms and TEM) and the homogeneous distribution and lack of clustering of iron atoms in the resulting materials (elemental analysis, magnetic measurements, pair distribution function (PDF), MAS-NMR and TEM mapping). The oxidation and spin state of single-iron atoms determined from their magnetic properties were confirmed by DFT calculations. This strategy might find straightforward applications in preparing versatile single atom catalysts, with improved efficiency compared to nanosized ones.
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Affiliation(s)
- Y Berro
- L2CM UMR CNRS 7053, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France; LPCT UMR CNRS 7019, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France; PRASE, Université Libanaise, Hadath, Lebanon
| | - S Gueddida
- LPCT UMR CNRS 7019, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France
| | - Y Bouizi
- L2CM UMR CNRS 7053, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France
| | - C Bellouard
- IJL UMR CNRS 7198, Université de Lorraine, 54000 Nancy, France.
| | - El-E Bendeif
- CRM2 UMR CNRS 7036, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France
| | - A Gansmuller
- CRM2 UMR CNRS 7036, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France
| | - A Celzard
- IJL UMR CNRS 7198, Université de Lorraine, 88000 Epinal, France
| | - V Fierro
- IJL UMR CNRS 7198, Université de Lorraine, 88000 Epinal, France
| | - D Ihiawakrim
- IPCMS UMR CNRS 7504, Université de Strasbourg, 67034 Strasbourg, France
| | - O Ersen
- IPCMS UMR CNRS 7504, Université de Strasbourg, 67034 Strasbourg, France
| | - M Kassir
- PRASE, Université Libanaise, Hadath, Lebanon
| | | | - S Lebegue
- LPCT UMR CNRS 7019, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France
| | - M Badawi
- LPCT UMR CNRS 7019, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France
| | - N Canilho
- L2CM UMR CNRS 7053, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France
| | - A Pasc
- L2CM UMR CNRS 7053, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France.
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Candolfi C, Lenoir B, Dauscher A, Bellouard C, Hejtmánek J, Santavá E, Tobola J. Spin fluctuations and superconductivity in Mo3Sb7. Phys Rev Lett 2007; 99:037006. [PMID: 17678319 DOI: 10.1103/physrevlett.99.037006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2007] [Indexed: 05/16/2023]
Abstract
Temperature dependences of the magnetic susceptibility, specific heat, and electrical resistivity have been measured for the Mo(3)Sb(7) compound in the 0.6-350 K range. This compound exhibits bulk superconductivity occurring at 2.25 K and follows the Kadowaki-Woods relation, A/gamma(2)=1.0 x 10(-5) microOmega x cm(K x mol/mJ)(2), as a heavy-fermion system does. We show, from experimental evidence and theoretical argument, that Mo(3)Sb(7) can be classified as a coexistent superconductor-spin fluctuation system. The McMillan equation including paramagnon effects was found to give an accurate estimation of the transition temperature.
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Affiliation(s)
- C Candolfi
- Laboratoire de Physique des Matériaux, Nancy Université, CNRS, Ecole Nationale Supérieure des Mines de Nancy, Parc de Saurupt, 54042 Nancy cedex, France.
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Tiusan C, Faure-Vincent J, Bellouard C, Hehn M, Jouguelet E, Schuhl A. Interfacial resonance state probed by spin-polarized tunneling in epitaxial Fe/MgO/Fe tunnel junctions. Phys Rev Lett 2004; 93:106602. [PMID: 15447433 DOI: 10.1103/physrevlett.93.106602] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2004] [Indexed: 05/24/2023]
Abstract
The direct impact of the electronic structure on spin-polarized transport has been experimentally proven in high-quality Fe/MgO/Fe epitaxial magnetic tunnel junctions, with an extremely flat bottom Fe/MgO interface. The voltage variation of the conductance points out the signature of an interfacial resonance state located in the minority band of Fe(001). When coupled to a metallic bulk state, this spin-polarized interfacial state enhances the band matching at the interface and therefore increases strongly the conductivity in the antiparallel magnetization configuration. Consequently, the tunnel magnetoresistance is found to be positive below 0.2 V and negative above. On the other hand, when the interfacial state is either destroyed by roughness-related disorder or not coupled to the bulk, the magnetoresistance is almost independent on the bias voltage.
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Affiliation(s)
- C Tiusan
- Laboratoire de Physique des Matériaux, BP 239, F-54506 Vandoeuvre lès Nancy, France
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Tillement O, Illy-cherrey S, Dubois JM, Begin-colin S, Massicot F, Schneider R, Fort Y, Ghanbaja J, Bellouard C, Belin-ferre E. Synthesis and properties of nearly single-shell nickel clusters in amorphous aluminium oxides. ACTA ACUST UNITED AC 2002. [DOI: 10.1080/01418610208240009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Bellouard C, Rapp HD, George B, Mangin S, Marchal G, Ousset JC. Negative spin-valve effect in Co65Fe35/Ag/(Co65Fe35)50Gd50 trilayers. Phys Rev B Condens Matter 1996; 53:5082-5085. [PMID: 9984095 DOI: 10.1103/physrevb.53.5082] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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